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15 Cards in this Set
- Front
- Back
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When does the arcuate nucleus of the hypothalamus begin secreting GnRH?
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The second trimester.
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Are any gonadotropins secreted during childhood?
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Yes, small amts, but the axis in boys is more profoundly suppressed.
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What is the first measurable event indicating onset of puberty?
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A striking increase in gonadotropin during sleep.
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What is the endocrinologic marker of adult reproductive function in women?
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Positive feedback, which is the ability of the pituitary to respond to high levels of female sex hormones w/ a surge of secretory activity.
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When is a reliable positive feedback mechanism established in females?
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12-18 mos after menarche.
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What is adrenarche, and when does it occur?
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Adrenarche is the adult pattern of adrenal cortex hormone secretion; activities 17-20desmolase and 17-hydroxylase increase. This predates puberty (b/w 6 & 9 yrs).
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Lesions where in the brain can trigger precocious puberty and why?
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Lesions in the posterior hypothalamus; studies implicate "neuropeptide Y" and GABA pathways serve to inhibit puberty.
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What is the critical weight and body composition hypothesis?
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It predicts that menarche won't occur until a critical wt (48 kg or 106 lb) & sufficiently high % body fat (24%) are achieved.
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What is Leptin?
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A protein product of adipose tissue that may have a permissive role in the onset of puberty: gene/receptor mutations have been assoc w/ delayed puberty.
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What is the role of hyperinsulinemia and insulin resistance in puberty?
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Both of these are assoc w/ obesity and somehow mediate the onset of puberty.
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What is the first sign of pubertal development in girls?
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Breast Budding
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When does menarche occur?
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About two years after onset of puberty.
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What is the first sign of pubertal development in boys?
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Enlargement of the gonads.
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What are the two effects of gonadal steroids on pubertal growth?
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1) Induce inc in GH secretion, which stimulates IGF-I from liver.
2) Stimulate local production of IGF-I and other growth factors in cartilage and bone. |
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Which type of gonadal steroids is necessary for normal skeletal growth and maturation in both girls and boys?
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Estrogen
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